Attwood ST33-20-5 Stainless Steel Gas Spring, 15 Inch Extended, 20 LB Boat Hatch Lift Support

The Attwood ST33-20-5 is a stainless steel gas spring built to hold boat hatches, deck lids, livewell covers, and line lockers open safely and smoothly. The pressure tube and rod are made from tough #316 stainless steel alloy, with all other exposed components finished in stainless steel or marine-grade composite, making this gas spring well suited to saltwater environments and other moisture-prone areas where corrosion resistance and long-term durability matter.

This unit is rated at 20 pounds of force with a 5.5 inch stroke, extending to 15 inches overall and compressing down to 9.5 inches. The 8mm rod pairs with a 10mm composite socket end for a secure, low-maintenance connection point. It ships as a single gas spring, ready to install as a direct replacement wherever a compatible stroke, force rating, and end-fitting size are required.

Common applications include deck hatches, storage lid supports, livewell lids, and line locker covers on boats where a reliable, corrosion-resistant lift assist is needed.

Specifications

• Brand: Attwood
• Manufacturer Part Number: ST33-20-5
• Product Type: Gas Spring (Stainless Steel)
• Material: Stainless steel (#316 alloy) with marine-grade composite components
• Stroke Length: 5.5 inches
• Compressed Length: 9.5 inches
• Extended Length: 15 inches
• Force Rating: 20 pounds
• Rod Diameter: 8 millimeters
• Socket Type: 10 millimeters, composite
• Thread Type: Metric
• Fastener Size: 5/16 inch
• Item Dimensions: 2.12 x 0.75 x 22.5 inches
• Weight: 0.552 pounds
• Package Quantity: 1

Frequently Asked Questions

What is the Attwood ST33-20-5 used for? The Attwood ST33-20-5 is a stainless steel gas spring used to hold boat hatches, deck lids, livewell covers, and line lockers open, providing controlled, assisted lift.

What force rating does this gas spring have? The ST33-20-5 is rated at 20 pounds of force, which determines how much weight it can support when holding a hatch or lid open.

What are the extended and compressed lengths of the ST33-20-5? This gas spring extends to 15 inches and compresses down to 9.5 inches, with a stroke length of 5.5 inches.

Is the ST33-20-5 suitable for saltwater use? Yes, the pressure tube and rod are made from #316 stainless steel alloy, with all other exposed parts in stainless steel or marine-grade composite, making the ST33-20-5 well suited to saltwater and other moisture-prone marine environments.

What is the rod diameter on this gas spring? The Attwood ST33-20-5 has an 8mm rod diameter, paired with a 10mm composite socket end fitting.

How much does the ST33-20-5 gas spring weigh? This gas spring weighs 0.552 pounds.

What is the overall size of the ST33-20-5? The unit measures 2.12 x 0.75 x 22.5 inches in overall item dimensions.

How many gas springs come in one package? One Attwood ST33-20-5 gas spring is included per package.

What material are the end fittings made of on this gas spring? The ST33-20-5 uses a 10mm composite socket-type end fitting, while the main tube and rod are stainless steel.

Where is the ST33-20-5 gas spring typically installed? Common installation points include deck hatches, storage lid supports, livewell lids, and line locker covers on boats.